DISEASED OF THE SKIN. 461 



The sweat j2:laiicls of the horse, like those of man, Jire composed of 

 biiuple tubes, wliich extend {h>\vn throii^li the cuticle and dermis in a 

 spiral manner, and are coiled into balls in the deepei* layer of the 

 true skin. In addition to their importance in throwing olTensive 

 waste products out of the system, these grlands tend to cool the skin 

 and the entire eccmomy of the aninud throu<;h the evaporation of 

 their AvateiT secretion. Their activity is theiefore a matter of no 

 small moment, as besides re^dating the animal heat and excreting^ 

 impurities, they influence larjrely the internal orji^ans throuji;ii the 

 intimate sympathy maintained between them and the skin. 



Diseases of the skin may be conveniently <livided, accordin<r to 

 their most marked features, into — 



(1) Those in which conc^estion and inflammation arc the most 

 marked features varyinjr according: to the gra<l(i or form into (a) 

 con«restion with simple redness, dryness, and heat, but no eruption 

 (erythema) ; (h) infiammation with red-pointed elevations, but no 

 blisters (pai)ules) ; (r) inflammation with fine, conical elevations, 

 each surmounted by a minute blister (vesicle); (d) inflammation 

 w ith a similar eruption but with lai<rer blisters, like half a pea and 

 upwards (bulla') ; (e) inflammation with a similar erupti(m, but 

 with a small s;ic of white, creamy pus on the summit of each eleva- 

 tion (pustules) ; (/) the formation of pustules implicatin«r the super- 

 ficial layer of the true skin, a small portion of which dies an<l is 

 thrown off as a slojigh. or "core" (boils); ('«7) the formation of 

 round, nodular, transient swellings in the true skin (tubercles) ; and 

 (A) the excessive production of scaler, or dandruff (scaly or s<jua- 

 mous affections). 



(2) Dis<»ases in which there are only deranged si'usiitions of itch- 

 ing, heat, tenderness, etc. (neurosis). 



(3) Diseased gro\\ths. such as waits, callosities, horny growths, 

 cancer, etc. 



(4) Diseases from parasites, animal and vegetable. 



(5) Diseases connected with a specific poison, such as horsepox, 

 erysipelas, anthrax, farcy, or cutaneous glanders, et^'. 



((')) Physical injuries, like wounds, burns, scalds, etc; 



CONGESTION (RED EFFLORESCENCE, OR ERYTHEMA). 



This is a congested or slightly in(lame<l condition of the skin, unat- 

 ten<le(l with any eruption. The pait is slightly swollen, hot, tender, 

 or itchy, and dry, and if the skin is white there is ledness The red- 

 ness is effaced by pre.s.sure, but reappears instantly when it is re- 

 moved. Kxcejit in transient cases the hairs mv liable to hv shed. 

 It may he looked on as the first stage of inflammation, and therefore 

 when it becomes aggravated it may merge in j)art or in whole into a 

 papular, vesicular, or i)ustular eruption. 



